Portable electric power source



FIG. 1 is a perspective view of a portable electric power source showing our new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a right side view thereof; and,

FIG. 7 is a left side view thereof.

The broken lines through the drawing figures are included for the purpose of illustrating portions of the power source that form no part of the claimed design. 

The ornamental design for a portable electric power source, as shown and described. 